Q: A 50.0 g sample of water is heated from 20.0 °C to 30.0 °C. How much heat is absorbed? (Specific heat of water = $$4.184\ \mathrm{J/g\ ^\circ C})$$

$$q = 50.0 \times (30.0 - 20.0) \times 4.184 = 2092\ \mathrm{J}$$

Q: A calorimeter is used to measure the energy content of food. If burning a 2.0 g sample of food raises the temperature of 100.0 g of water by 10.0 °C, how many calories does the food contain? ($$1\ \mathrm{cal} = 4.184\ \mathrm{J}$$, specific heat of water = $$1.00\ \mathrm{cal/g\ ^\circ C})$$

$$q = 100.0 \times 10.0 \times 1.00 = 1000\ \mathrm{cal}$$

Q: A 24.8 g sample of metal absorbs 275 J of energy, raising its temperature from 20.2 °C to 24.5 °C. What is the specific heat of the metal?

$$SH = \frac{275}{24.8 \times (24.5 - 20.2)} = 2.72\ \mathrm{J/g\ ^\circ C}$$

Q: A food label lists 130 Calories per serving. How many kilojoules (kJ) is this? ($$1\ \mathrm{Cal} = 4.184\ \mathrm{kJ})$$

$$130 \times 4.184 = 544\ \mathrm{kJ}$$

Question 1

A patient has a body temperature of 39.5 °C. What is this temperature in Kelvin?

Accepted Answer

$$K = 39.5 + 273 = 312.5\ \mathrm{K}$$

Question 2

Which of the following best describes the energy transformation when water flows over a dam?

Accepted Answer

Potential energy is converted to kinetic energy.

Question 3

A 50.0 g sample of water is heated from 20.0 °C to 30.0 °C. How much heat is absorbed? (Specific heat of water = $$4.184\ \mathrm{J/g\ ^\circ C})$$

Accepted Answer

$$q = 50.0 	imes (30.0 - 20.0) 	imes 4.184 = 2092\ \mathrm{J}$$

Question 4

Which of the following is an example of potential energy?

Accepted Answer

A compressed spring

Question 5

A calorimeter is used to measure the energy content of food. If burning a 2.0 g sample of food raises the temperature of 100.0 g of water by 10.0 °C, how many calories does the food contain? ($$1\ \mathrm{cal} = 4.184\ \mathrm{J}$$, specific heat of water = $$1.00\ \mathrm{cal/g\ ^\circ C})$$

Accepted Answer

$$q = 100.0 	imes 10.0 	imes 1.00 = 1000\ \mathrm{cal}$$

Question 6

Which of the following statements about specific heat is correct?

Accepted Answer

Water has a higher specific heat than most metals, which helps moderate Earth's climate.

Question 7

Which process is represented by the equation: $$\mathrm{H_2O(s)} \xrightarrow{+	ext{heat}} \mathrm{H_2O(l)}$$?

Accepted Answer

Melting

Question 8

A 24.8 g sample of metal absorbs 275 J of energy, raising its temperature from 20.2 °C to 24.5 °C. What is the specific heat of the metal?

Accepted Answer

$$SH = \frac{275}{24.8 	imes (24.5 - 20.2)} = 2.72\ \mathrm{J/g\ ^\circ C}$$

Question 9

Which type of radiation requires the most shielding to protect the human body?

Accepted Answer

Gamma ($$\gamma) $$rays

Question 10

Which of the following is a correct statement about the use of radioisotopes in medicine?

Accepted Answer

Radioisotopes with short half-lives are preferred because they decay quickly and minimize patient exposure.

Question 11

A food label lists 130 Calories per serving. How many kilojoules (kJ) is this? ($$1\ \mathrm{Cal} = 4.184\ \mathrm{kJ})$$

Accepted Answer

$$130 	imes 4.184 = 544\ \mathrm{kJ}$$

Question 12

Which of the following best describes the process of sublimation?

Accepted Answer

A solid changes directly to a gas without becoming a liquid.

Question 13

Which imaging technique does NOT involve nuclear radiation and is based on the absorption of energy by protons in hydrogen atoms?

Accepted Answer

Magnetic Resonance Imaging (MRI)

Question 14

Which of the following is the SI unit for measuring radiation activity?

Accepted Answer

Becquerel (Bq)

Question 15

Which of the following is a correct equation for converting Celsius to Kelvin?

Accepted Answer

$$T_K = T_C + 273$$

Question 16

Which of the following is a biological effect of ionizing radiation?

Accepted Answer

It can cause cancer by damaging rapidly dividing cells.

Question 17

A 70.0-kg adult burns 2100 kJ of energy by swimming for one hour. How many kilocalories (kcal) is this? ($$1\ \mathrm{kcal} = 4.184\ \mathrm{kJ})$$

Accepted Answer

$$2100 \div 4.184 = 502\ \mathrm{kcal}$$

Question 18

Which of the following is true about the calorie (cal)?

Accepted Answer

It is the amount of energy needed to raise the temperature of 1 g of water by 1 °C.

Matter and Energy: Temperature, Energy, and Nuclear Chemistry

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